Recently, research into direct water type water purifiers supplying hot water using instantaneous water heaters has been increasingly undertaken.
A conventional direct water type water purifier supplies hot water using a plurality of heating devices controlling the temperature of hot water by adjusting a level of power supplied to the heating devices with a fixed flow rate or adjusting the flow rate with a fixed amount of power being supplied to the heating devices.
However, a method of adjusting a level of power supplied to a plurality of heating devices or high-capacity heating devices may cause electromagnetic interference (EMI) and may cause harmonics and flickering, resulting in loss of control of discharge temperature within a predetermined narrow temperature range. Both of the two methods are required to discharge water passing through a hot water supply device through a drain until hot water having a target temperature is generated, thereby requiring a standby time for the generation of the hot water having the target temperature.
Further, the water inlet pressure of the conventional direct water type water purifier may vary according to installation areas and installation conditions. A direct water type hot water supply device 10 controlling the temperature of hot water by adjusting a flow rate or a level of power supplied to heaters may not generate hot water having a target temperature when water inlet pressure changes.